CHAPTER X. 



MANUFACTUKE OF BONE DUST AND OF BONE SUPEEPHOSPHATE 



(VITRIOLIZED BONES). 



The use of bone dust as a manure goes back to somewhat distant 

 times. It rapidly extended when Liebig advised that it should be 

 dissolved by sulphuric acid, so as to obtain more rapid and certain 

 effects. At the present time this product has to compete against 

 nitrate of soda and basic slag. Moreover, certain manufacturers 

 find it more advantageous to use bones in the manufacture of glue, 

 and then to transform them into superphosphate afterwards. 

 Whatever be the method of utilizing bones, it is indispensable 

 previously to free them from fat, as will be seen in the sequel. 



Chemical Compontion of Bones. — The bones which form the 

 framework of vertebrae, consist like all vegetable and animal matter 

 of organic elements, and of mineral elements of combustible matter, 

 and of ash. The combustible matter (moisture excluded) consists 

 essentially of ossein (yielding gelatine) and of fat. Bone ash consists 

 in great part of phosphate of lime. If the previously fat-extracted 

 bones be digested with dilute hydrochloric acid, the phosphate of 

 lime is dissolved, and a residue of ossein is obtained as a white 

 elastic translucid substance which consists of : — 



TABLE XLYIII.— CHEMICAL COMPOSITION OF OSSEIN. 



Carbon 



Hydrogen 



Nitrogen 



Sulphur 



Oxygen 



Per cent. 



50-1 



7-1 



18-8 



0-2 



24 -2 



100-4 



Ossein dissolves very slowly in boiling water when bones are boiled 

 with water, and more rapidly when treated in a close vessel under 

 pressure. By prolonging the operation for a sufficient length of 

 time the bones can be completely freed from ossein. A residue of 

 phosphate of lime is thus obtained with the initial form of the bone. 

 Finally, ossein may be extracted by boiling with dilute potash lye. 



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